$ git clone -n https://src.fedoraproject.org/rpms/kf6-purpose.git /var/lib/mock/f40-build-754807-117978/root/chroot_tmpdir/scmroot/kf6-purpose
Cloning into '/var/lib/mock/f40-build-754807-117978/root/chroot_tmpdir/scmroot/kf6-purpose'...
$ git fetch origin 5b488c67f257ff8d0c7279bddd3607a494a7c766:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf6-purpose
 * [new ref]         5b488c67f257ff8d0c7279bddd3607a494a7c766 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5b488c6 fix: add missing sources